The present invention relates to a bicycle head tube sealing structure fastened to the head tube of a bicycle to fix the top tube of the front fork in place by turning a screw to lift a packing block and to expand a split ring.
When the top tube of the front fork of a bicycle is inserted into the head tube, a head tube sealing device must be installed in the top end of the head tube to fix the top tube of the front fork in place. FIG. 1 shows a bicycle head tube sealing structure for this purpose. This bicycle head tube sealing structure comprises a locating plate fixedly fastened to the inside of the top tube of the front fork when the top tube of the front fork is inserted into the head tube, a screw inserted through a cap, which is fastened to the top end of the head tube, and the locating plate, and then threaded into a screw member inside the top tube of the front fork. The locating plate A is fastened to the inside of the top tube of the front fork by a high-pressure mechanism. If the locating plate is not accurately forced into position, it can not work properly and must be removed from the top tube of the front fork. However, removing the tilted locating plate from the top tube of the front fork is not easy, and the front fork may be damage during the dismantling process of the tilted locating plate.
The present invention has been accomplished to provide a bicycle head tube sealing structure which eliminates the aforesaid drawback. According to the preferred embodiment of the present invention, the bicycle head tube sealing structure comprises a plug cap at the top end of the head tube, a packing block disposed inside the top tube of the front fork, a screw inserted through the plug cap and threaded into the packing block, a stop plate mounted inside the top tube of the front fork, a spring mounted around the screw and stopped between the plug cap and the stop plate, and a split ring mounted around the screw between the stop plate and the conical packing block. Therefore, when the screw is turned in one direction, the conical packing block is forced upwards to squeeze the split ring against the stop plate, causing the top tube of the front fork firmly secured to the head tube. However, the top tube of the front fork can be conveniently disconnected from the head tube by turning the screw in the reversed direction to release the packing block from the split ring .